| 摘要 |
PURPOSE:To develop a means for preventing binder used at the time of forming the conventional immersion nozzle from change with working environment or variation of a permeable hole formed with aging. CONSTITUTION:The binder composed of self-curing high polymer phenol formaldehyde resin having 2-5 pieces of methyl group in the phenol 10 core body and 1/5-1/15 compared with general resol type phenol resin and a little hygroscopicity and containing the polymer of >=10000 average molecular wt. before curing, is used and further, by adding solvent having low hygroscopicity and >=200 deg.C b.p. to the above self-curing high polymer phenol formaldehyde resin, the change of plasticity of the binder due to the temp. and the moisture with the lapse of time is reduced and this can greatly contribute to stability of the permeable level in the gas permeable body and service life of the nozzle for continuous casting applying the gas permeable body having excellent permeable stability can be drastically improved. |
